• Title/Summary/Keyword: V-cracks

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Flexural Vibration Analysis of Mindlin Rectangular Plates Having V-notches or Sharp Cracks (V노치 또는 예리한 균열을 가지는 Mindlin 직사각형 평판의 휨 진동해석)

  • Kim, Joo-Woo;Jung, Eui-Young;Kim, Seung-Hyun
    • Proceedings of the Computational Structural Engineering Institute Conference
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    • 2003.04a
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    • pp.35-42
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    • 2003
  • This paper provides the first known flexural vibration data for thick (Mindlin) rectangular plates having V-notches. The V-notch has bending moment and shear force singularities at its sharp corner due to the transverse vibratory bending motion. Based upon Mindlin plate theory, in which transverse shear deformation and rotary inertia effects are considered, the Ritz procedure is employed with a hybrid set of admissible functions assumed for the rotational and transverse vibratory displacements. This set includes: (1) a mathematically complete set of admissible algebraic-trigonometric polynomials which guarantee convergence to exact frequencies as sufficient terms are retained; and (2) an admissible set of Mindlin corner functions which account for the bending moment and shear force singularities at the sharp corner of the V-notch. Extensive convergence studies demonstrate the necessity of adding the Mindlin corner functions to achieve accurate frequencies for rectangular plates having sharp V-notches.

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Analysis of Cracks on Flange Bolts at 154kV Transmission Line Hollow Supporter (154kV 송전선로 관형지지물 플랜지 볼트 균열 분석기술 현장적용)

  • Lee, Jaehong
    • KEPCO Journal on Electric Power and Energy
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    • v.7 no.1
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    • pp.59-62
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    • 2021
  • 관형지지물은 단일 강관 기둥 형태의 송전탑으로 강관은 상하 여러 개의 프레임으로 분할되어 플랜지부에서 볼트로 체결된다. 신설 송전선로 관형지지물 플랜지 연결부에서 가압전 조립 볼트 절손이 발견됨에 따라 강관도괴방지 대책 수립을 위한 손상원인분석 기술지원을 수행하였다. 본 건에 대해 파손면·균열 분석 기술을 통해 제작과정 상의 문제가 있었음을 확인하였다.

Determination of Stress Intensity Factors for Interface Cracks in Dissimilar Materials Using the RWCIM (상반일 등고선 적분법을 이용한 이종재 접합계면 균열의 응력강도계수 결정)

  • 조상봉;정휘원;김진광
    • Journal of the Korean Society for Precision Engineering
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    • v.17 no.5
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    • pp.180-185
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    • 2000
  • An interface V-notched crack problem can be formulated as a eigenvalue problem. there are the eigenvalues which give stress singularities at the V-notched crack tip. The RWCIM is a method of calculating the eigenvector coefficients associated with eigenvalues for a V-notched crack problem. Obtaining the stress intensity factors for an interface crack in dissimilar materials is examined by the RWCIM. The results of stress intensity factors for an interface crack are compared with those of the displacement extrapolation method by the BEM

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Study on Surface Crack Propagation Behaviour of Mild Steel Weldment in Synthetic Sea Water (인공해수중에서 연강 용접부의 표면구열 성장거동)

  • 이종기;정세희
    • Transactions of the Korean Society of Mechanical Engineers
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    • v.14 no.2
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    • pp.492-501
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    • 1990
  • It was known that the fracture incidences of offshore structure were mostly originated from the surface defects. Especially, in the case of the welded structures, since the welded region has some defects and incomplete beads which are apt to behave like the surface cracks, it has been necessary to evaluate the environmental effects on crack growth at HAZ for the design crack growth behaviour at multi-pall HAZ for SWS41 steel under free corrosion and cathodic protection(-0.9V vs Ag/Agcl) conditions. The results are summarized as follows ; (1) Crack growth rate of the as weld in air was faster than that of the parent and PWHT specimens over all .DELTA.K rang. (2) In free corrosion test, surface crack growth rate of the as welded was decreased in comparison with that of the parents. (3) In fatigue test under cathodic protection, cathodic electric potential(-0.9V vs Ag/Agcl) for the SWS41 steel parent was effective, while for the as welded ineffective. (4) There was a tendency that the exponent(m) of the Paris' equation was decreased in order of microhardness magnititude in air and under cathodic protection conditions and vise versa in free corrosion. (5) Fracture surface has dimples and ductile striations in air test, but transgranular cracks and brittle striations under cathodic protection test.

Evaluating stability of dam foundations by borehole and surface survey using Step Frequency Radar

  • Jha Prakash C.;Balasubramaniam V. R.;Nelliat Sandeep;Sivaram Y. V.;Gupta R. N.
    • 한국지구물리탐사학회:학술대회논문집
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    • 2003.11a
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    • pp.328-334
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    • 2003
  • Evaluating stability of dam foundations is one of the prime areas of any rock engineering investigations. Despite best engineering efforts in the design and construction of dam foundations, the foundation regime of a constructed dam suffers deterioration due to continuous erosion from backwater current of dam discharge and dynamic effects of loading and unloading process. Even during construction, development of frequent cracks due to sudden thermal cooling of concrete blocks is not uncommon. This paper presents two case studies from India and Bhutan. In the first case, the back current of water discharge from the Srisailam dam in India had continuously eroded the apron and has eaten into the dam foundation. In the second case with dam construction at Tala Hydroelectric Project in Bhutan, sudden overflow of river during the construction stage of dam had led to development of three major cracks across the dam blocks. This was ascribed to adiabatic cooling effect of concrete blocks overlain by chilled water flow. Non-destructive evaluation of rock mass condition in the defect regime by the borehole GPR survey helped in arriving at the crux so as to formulate appropriate restoration plan.

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Analysis of Propagating Crack Along Interface of Isotropic-Orthotropic Bimaterial by Photoelastic Experiment

  • Lee, K.H.;Shukla, A.;Parameswaran, V.;Chalivendra, V.;Hawong, J.S.
    • Proceedings of the KSME Conference
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    • 2001.06a
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    • pp.102-107
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    • 2001
  • Interfacial cracks between an isotropic and orthotropic material, subjected to static far field tensile loading are analyzed using the technique of photoelasticity. The fracture parameters are extracted from the full-field isochromatic data and the same are compared with that obtained using boundary collocation method. Dynamic Photoelasticity combined with high-speed digital photography is employed for capturing the isochromatics in the case of propagating interfacial cracks. The normalized stress intensity factors for static crack is greater when $\alpha=90^{\circ}C$ (fibers perpendicular to the interface) than when $\alpha=0^{\circ}C$ (fiber parallel to the interface) and those when $\alpha=90^{\circ}C$ are similar to ones of isotropic material. The dynamic stress intensity factors for interfacial propagating crack are greater when $\alpha=0^{\circ}C$ than $\alpha=90^{\circ}C$. The relationship between complex dynamic stress intensity factor $|K_D|$ and crack speed C is similar to that for isotropic homogeneous materials, the rate of increase of energy release rate G or $|K_D|$ with crack speed is not as drastic as that reported for homogeneous materials.

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Joint Properties of Stainless Steel and Titanium Alloys Additive Manufactured on Medium Entropy Alloys (중엔트로피 합금 기지 위에 적층조형된 스테인리스강과 타이타늄 합금의 접합특성 분석)

  • Park, Chan Woong;Adomako, Nana Kwabena;Lee, Min Gyu;Kim, Jeoung Han
    • Journal of Powder Materials
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    • v.26 no.4
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    • pp.319-326
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    • 2019
  • Additive manufacturing (AM) is a highly innovative method for joining dissimilar materials for industrial applications. In the present work, AM of STS630 and Ti-6Al-4V powder alloys on medium entropy alloys (MEAs) NiCrCo and NiCrCoMn is studied. The STS630 and Ti64 powders are deposited on the MEAs. Joint delamination and cracks are observed after the deposition of Ti64 on the MEAs, whereas the deposition of STS630 on the MEAs is successful, without any cracks and joint delamination. The microstructure around the fusion zone interface is characterized by scanning electron microscopy and X-ray diffraction. Intermetallic compounds are formed at the interfacial regions of MEA-Ti64 samples. In addition, Vicker's hardness value increased dramatically at the joint interface between MEAs and Ti-6Al-4V compared to that between MEAs and STS630. This result is attributed to the brittle nature of the joint, which can lead to a decrease in the joint strength.

Flexural Vibrations of Rectangular Plates Having V-notches or Sharp Cracks (V노치 또는 예리한 균열을 가지는 직사각형 평판의 굽힘 진동)

  • 정희영;정의영;김주우
    • Transactions of the Korean Society for Noise and Vibration Engineering
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    • v.14 no.4
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    • pp.336-343
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    • 2004
  • This paper reports the first known free vibration data for thin rectangular plates with V-notches. The classical Ritz method is employed with two sets of admissible functions assumed for the transverse vibratory displacements. These sets include (1) mathematically complete algebraic-trigonometric polynomials which guarantee convergence to exact frequencies as sufficient terms are retained, and (2) corner functions which account for the bending moment singularities at the sharp reentrant corner of the Y-notch. Extensive convergence studies summarized herein confirm that the corner functions substantially enhance the convergence and accuracy of nondirectional frequencies for rectangular plates having the V-notch. In this paper, accurate frequencies and normalized contours of vibratory transverse displacement are presented for various notched plates, so that the effect of corner stress singularities may be understood.

V-notched elements under mode II loading conditions

  • Sapora, Alberto;Cornetti, Pietro;Carpinteri, Alberto
    • Structural Engineering and Mechanics
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    • v.49 no.4
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    • pp.499-508
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    • 2014
  • We apply the Finite Fracture Mechanics criterion to address the problem of a V-notched structure subjected to mode II loading, i.e., we provide a way to determine the direction and the load at which a crack propagates from the notch tip and express the critical conditions in terms of the generalized stress intensity factor. Weight functions for V-notch emanated cracks available in the literature allow us to implement the fracture criterion proposed in an almost completely analytical manner: the determination of the critical load and the direction of crack growth is reduced to a stationary point problem. A comparison with experimental data presented in the Literature concludes the paper.

Effect of Temperature on Joint Movement of JPCP at Its Early Age (재령초기 콘크리트포장 줄눈거동에 미치는 온도의 영향)

  • Choi, Ki-Hyo;Jeong, Jin-Hoon;Chun, Sung-Han;Park, Moon-Gil
    • 한국방재학회:학술대회논문집
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    • 2007.02a
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    • pp.340-343
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    • 2007
  • The temperature variation of concrete pavement at early-age significantly affects the initiation and movement of joint cracks. For this analysis, we have built on IIA(Incheon International Airport) concrete pavement construction zone, and we measured the temperature and movement of the concrete slabs by using thermocouples, moisture sensors, V/W strain gages, and Demac discs. The analysis results showed that pavement's temperature significantly affected the joint movement. The widths of the joint cracks increased at evening and early in the morning when the temperature dropped but, those decreased in the day time when the temperature rose because of the effect of thermal expansion of the concrete slabs. The movements of the joints where the cracks never developed showed opposite trend to the cracked joints.

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